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	$195.54	7.356%	$209.9239	$209.92	$209.90	$209.90
Purchase #2	$52.47	4.597%	$54.882	$54.88	$54.90	$54.90
Purchase #3	$222.92	5.326%	$234.7927	$234.79	$234.80	$234.80
Purchase #4	$228.88	4.438%	$239.0377	$239.04	$239.05	$239.00
Purchase #5	$146.88	6.234%	$156.0365	$156.04	$156.05	$156.00
Purchase #6	$96.70	13.473%	$109.7284	$109.73	$109.75	$109.70
Purchase #7	$112.83	5.387%	$118.9082	$118.91	$118.90	$118.90
7 purchase totals =	$1,056.22		$1,123.3094	$1,123.31	$1,123.35	$1,123.20