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	$200.47	4.596%	$209.6836	$209.68	$209.70	$209.70
Purchase #2	$38.67	6.303%	$41.1074	$41.11	$41.10	$41.10
Purchase #3	$176.31	11.513%	$196.6086	$196.61	$196.60	$196.60
Purchase #4	$112.55	13.503%	$127.7476	$127.75	$127.75	$127.70
Purchase #5	$197.39	4.323%	$205.9232	$205.92	$205.90	$205.90
Purchase #6	$233.34	13.408%	$264.6262	$264.63	$264.65	$264.60
Purchase #7	$66.56	7.192%	$71.347	$71.35	$71.35	$71.30
7 purchase totals =	$1,025.29		$1,117.0436	$1,117.05	$1,117.05	$1,116.90