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	$197.88	12.782%	$223.173	$223.17	$223.15	$223.20
Purchase #2	$38.32	13.774%	$43.5982	$43.60	$43.60	$43.60
Purchase #3	$67.51	4.711%	$70.6904	$70.69	$70.70	$70.70
Purchase #4	$181.78	3.851%	$188.7803	$188.78	$188.80	$188.80
Purchase #5	$195.74	8.660%	$212.6911	$212.69	$212.70	$212.70
Purchase #6	$55.95	7.786%	$60.3063	$60.31	$60.30	$60.30
Purchase #7	$236.91	11.818%	$264.908	$264.91	$264.90	$264.90
7 purchase totals =	$974.09		$1,064.1473	$1,064.15	$1,064.15	$1,064.20