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	$43.38	4.543%	$45.3508	$45.35	$45.35	$45.40
Purchase #2	$79.57	13.436%	$90.261	$90.26	$90.25	$90.30
Purchase #3	$227.53	11.672%	$254.0873	$254.09	$254.10	$254.10
Purchase #4	$150.46	5.726%	$159.0753	$159.08	$159.10	$159.10
Purchase #5	$105.28	3.744%	$109.2217	$109.22	$109.20	$109.20
Purchase #6	$7.53	11.778%	$8.4169	$8.42	$8.40	$8.40
Purchase #7	$33.57	10.535%	$37.1066	$37.11	$37.10	$37.10
7 purchase totals =	$647.32		$703.5196	$703.53	$703.50	$703.60