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	$53.86	8.503%	$58.4397	$58.44	$58.45	$58.40
Purchase #2	$200.88	7.249%	$215.4418	$215.44	$215.45	$215.40
Purchase #3	$185.51	8.834%	$201.898	$201.90	$201.90	$201.90
Purchase #4	$89.82	10.675%	$99.4083	$99.41	$99.40	$99.40
Purchase #5	$232.33	5.717%	$245.6123	$245.61	$245.60	$245.60
Purchase #6	$56.35	10.760%	$62.4133	$62.41	$62.40	$62.40
Purchase #7	$152.78	11.380%	$170.1664	$170.17	$170.15	$170.20
7 purchase totals =	$971.53		$1,053.3798	$1,053.38	$1,053.35	$1,053.30