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	$191.96	10.197%	$211.5342	$211.53	$211.55	$211.50
Purchase #2	$81.50	4.511%	$85.1765	$85.18	$85.20	$85.20
Purchase #3	$164.45	4.428%	$171.7318	$171.73	$171.75	$171.70
Purchase #4	$105.91	3.218%	$109.3182	$109.32	$109.30	$109.30
Purchase #5	$220.77	11.402%	$245.9422	$245.94	$245.95	$245.90
Purchase #6	$220.58	12.648%	$248.479	$248.48	$248.50	$248.50
Purchase #7	$88.59	3.684%	$91.8537	$91.85	$91.85	$91.90
7 purchase totals =	$1,073.76		$1,164.0356	$1,164.03	$1,164.10	$1,164.00