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	$90.76	4.503%	$94.8469	$94.85	$94.85	$94.80
Purchase #2	$82.59	13.631%	$93.8478	$93.85	$93.85	$93.80
Purchase #3	$245.44	7.606%	$264.1082	$264.11	$264.10	$264.10
Purchase #4	$53.49	4.576%	$55.9377	$55.94	$55.95	$55.90
Purchase #5	$238.72	11.543%	$266.2754	$266.28	$266.30	$266.30
Purchase #6	$180.30	4.129%	$187.7446	$187.74	$187.75	$187.70
Purchase #7	$79.90	4.643%	$83.6098	$83.61	$83.60	$83.60
7 purchase totals =	$971.20		$1,046.3704	$1,046.38	$1,046.40	$1,046.20