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	$176.46	9.465%	$193.1619	$193.16	$193.15	$193.20
Purchase #2	$111.72	3.200%	$115.295	$115.30	$115.30	$115.30
Purchase #3	$114.53	11.156%	$127.307	$127.31	$127.30	$127.30
Purchase #4	$151.44	7.412%	$162.6647	$162.66	$162.65	$162.70
Purchase #5	$133.97	13.180%	$151.6272	$151.63	$151.65	$151.60
Purchase #6	$185.85	5.766%	$196.5661	$196.57	$196.55	$196.60
Purchase #7	$212.62	7.639%	$228.862	$228.86	$228.85	$228.90
7 purchase totals =	$1,086.59		$1,175.4839	$1,175.49	$1,175.45	$1,175.60