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	$113.51	5.282%	$119.5056	$119.51	$119.50	$119.50
Purchase #2	$231.88	13.474%	$263.1235	$263.12	$263.10	$263.10
Purchase #3	$180.80	5.285%	$190.3553	$190.36	$190.35	$190.40
Purchase #4	$149.54	6.224%	$158.8474	$158.85	$158.85	$158.80
Purchase #5	$62.53	12.561%	$70.3844	$70.38	$70.40	$70.40
Purchase #6	$90.39	9.871%	$99.3124	$99.31	$99.30	$99.30
Purchase #7	$98.26	12.710%	$110.7488	$110.75	$110.75	$110.70
7 purchase totals =	$926.91		$1,012.2774	$1,012.28	$1,012.25	$1,012.20