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	$211.54	3.582%	$219.1174	$219.12	$219.10	$219.10
Purchase #2	$148.54	5.152%	$156.1928	$156.19	$156.20	$156.20
Purchase #3	$43.41	11.467%	$48.3878	$48.39	$48.40	$48.40
Purchase #4	$134.35	13.685%	$152.7358	$152.74	$152.75	$152.70
Purchase #5	$116.95	9.698%	$128.2918	$128.29	$128.30	$128.30
Purchase #6	$66.46	7.736%	$71.6013	$71.60	$71.60	$71.60
Purchase #7	$210.94	6.612%	$224.8874	$224.89	$224.90	$224.90
7 purchase totals =	$932.19		$1,001.2143	$1,001.22	$1,001.25	$1,001.20