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	$88.28	7.443%	$94.8507	$94.85	$94.85	$94.90
Purchase #2	$116.61	5.607%	$123.1483	$123.15	$123.15	$123.10
Purchase #3	$224.89	8.651%	$244.3452	$244.35	$244.35	$244.30
Purchase #4	$122.52	5.216%	$128.9106	$128.91	$128.90	$128.90
Purchase #5	$181.56	8.138%	$196.3354	$196.34	$196.35	$196.30
Purchase #6	$72.48	4.197%	$75.522	$75.52	$75.50	$75.50
Purchase #7	$181.25	4.428%	$189.2758	$189.28	$189.30	$189.30
7 purchase totals =	$987.59		$1,052.3880	$1,052.40	$1,052.40	$1,052.30