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	$211.91	3.521%	$219.3714	$219.37	$219.35	$219.40
Purchase #2	$154.92	4.755%	$162.2864	$162.29	$162.30	$162.30
Purchase #3	$80.80	3.530%	$83.6522	$83.65	$83.65	$83.70
Purchase #4	$196.40	4.606%	$205.4462	$205.45	$205.45	$205.40
Purchase #5	$171.88	5.361%	$181.0945	$181.09	$181.10	$181.10
Purchase #6	$79.64	12.418%	$89.5297	$89.53	$89.55	$89.50
Purchase #7	$119.61	4.421%	$124.898	$124.90	$124.90	$124.90
7 purchase totals =	$1,015.16		$1,066.2784	$1,066.28	$1,066.30	$1,066.30