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	$196.91	7.586%	$211.8476	$211.85	$211.85	$211.80
Purchase #2	$226.83	7.536%	$243.9239	$243.92	$243.90	$243.90
Purchase #3	$74.38	11.109%	$82.6429	$82.64	$82.65	$82.60
Purchase #4	$128.57	4.527%	$134.3904	$134.39	$134.40	$134.40
Purchase #5	$70.72	12.197%	$79.3457	$79.35	$79.35	$79.30
Purchase #6	$119.69	6.559%	$127.5405	$127.54	$127.55	$127.50
Purchase #7	$191.34	9.364%	$209.2571	$209.26	$209.25	$209.30
7 purchase totals =	$1,008.44		$1,088.9481	$1,088.95	$1,088.95	$1,088.80