Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$197.97	12.663%	$223.0389	$223.04	$223.05	$223.00
Purchase #2	$101.79	12.579%	$114.5942	$114.59	$114.60	$114.60
Purchase #3	$123.55	11.634%	$137.9238	$137.92	$137.90	$137.90
Purchase #4	$128.39	3.464%	$132.8374	$132.84	$132.85	$132.80
Purchase #5	$174.35	6.174%	$185.1144	$185.11	$185.10	$185.10
Purchase #6	$128.58	3.467%	$133.0379	$133.04	$133.05	$133.00
Purchase #7	$115.88	10.270%	$127.7809	$127.78	$127.80	$127.80
7 purchase totals =	$970.51		$1,054.3275	$1,054.32	$1,054.35	$1,054.20