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	$96.49	13.618%	$109.63	$109.63	$109.65	$109.60
Purchase #2	$55.76	4.186%	$58.0941	$58.09	$58.10	$58.10
Purchase #3	$219.59	6.423%	$233.6943	$233.69	$233.70	$233.70
Purchase #4	$238.48	11.264%	$265.3424	$265.34	$265.35	$265.30
Purchase #5	$223.91	3.733%	$232.2686	$232.27	$232.25	$232.30
Purchase #6	$173.77	13.222%	$196.7459	$196.75	$196.75	$196.70
Purchase #7	$13.65	11.566%	$15.2288	$15.23	$15.25	$15.20
7 purchase totals =	$1,021.65		$1,111.0041	$1,111.00	$1,111.05	$1,110.90